(a) Field of the Invention
The present invention relates to a catalyst precursor composition for electroless plating, and a method of preparing transparent electromagnetic interference shielding material (hereinafter, referred to as “EMI” shielding material) using the same. More specifically, the catalyst precursor composition includes a UV (ultraviolet) curable resin with excellent adhesiveness to a base material, thereby eliminating the need for an additional pre-treatment in preparing the EMI shielding material. Thus, the present invention provides a catalyst precursor composition to easily prepare the EMI shielding material, and a preparation method for EMI shielding material using the same.
(b) Description of the Related Art
A plasma display panel (hereinafter referred to as “PDP”) has an electrode providing a whole surface of a front glass thereof with signals and electric power, which produces much electromagnetic radiation in operation compared to other display devices.
Thus, it is necessary for the PDP to be equipped with a filter for shielding harmful electromagnetic waves generated in operating the PDP. The filter consists of several films laminated on glass, such as an anti-reflection film (hereinafter referred to as “AR film”), a near infrared ray shield film (hereinafter referred to as “NIR film”), a Neon-cut film, an EMI shield film, etc.
The EMI shielding material with good transparency is preferable to enable penetration of visible light. The EMI shielding material can be prepared by adhering conductive metals such as Copper, Silver, and Nickel on a transparent base material in a lattice pattern. The adhering methods of conductive metals on a substrate are classified into a dry method including a sputtering method and vacuum deposition, and a wet method including electroless plating, etc. Because the dry method requires expensive manufacturing equipments, the inexpensive wet method is most widely used.
In the electroless plating method, the plating reaction is initiated by contacting a plating solution with a catalyst, and thus metal is only plated on the catalyst. Printing of the catalyst on the transparent base material in a lattice pattern and then performing electroless plating produces the transparent EMI shielding material.
In general, because a catalyst for electroless plating is prepared in water, it is not easily adhered to the base material which is smooth and hydrophobic. Thus, the base material must be pre-treated to increase its surface roughness and hydrophilic properties by etching, etc. However, the pre-treatment cause a lack of uniformity and visibility in the base material surface.
Japanese Laid-Open Publication No. 2000-311527 discloses a method of preparing a transparent conductive film by printing a resin composition containing a catalyst for electroless plating on a base material to form a pattern, and then forming a conductive metal layer on the pattern by an electroless plating method. The method is advantageous in that it easily provides various kinds of patterned metal layers. However, an electroless catalyst must be obtained through a complicated process, and a layer that is receptive to the resin composition must be made on the surface of the base material before electroless plating takes place.
Japanese Laid-Open Publication No. 2001-177292 discloses a method of preparing the transparent conductive film by coating a hydrophobic transparent resin including a catalyst for electroless plating on the base material, and then performing electroless plating. The transparent metal pattern is obtained by performing electroless plating after coating a plating-resist compound on the resin layer, or by coating a photoresist compound on the electroless plated surface, irradiating light through a photomask, and then etching. In most cases, hydrophobic resins are used to adhere to the hydrophobic base material, but the method has a problem in that a transparent conductive film with high endurance cannot be obtained due to low adhesiveness. In addition, the process of shaping the metal pattern is complicated, requires expensive devices such as a photomask, and uses a non-aqueous plating solution, thereby increasing the production costs.
Japanese Laid-Open Publication No. 2002-185184 discloses a method of preparing the transparent EMI shielding material by printing a resin composition containing an electroless plating catalyst on a base material in a lattice pattern, and then performing electroless plating. In this case, a transparent pattern is made by a printing method, thereby requiring no expensive devices such as a photomasking machine, but a base material must be pre-treated with a receptive layer or an anchoring layer before plating in order to easily adhere the resin composition to the base material. In particular, it takes about three days to cure an anchoring layer coated by a two-component solution, thereby making it difficult to apply to the practical field.